Wall



Dec. 17, 1929. E. BERLINER WALL Filed June 15, 1927 gwumtoo Emil9 Berliner Patented Dec. 17, 1929 UNITED STATES PATENT OFFICE WALL Application filed June 15,

My invention relates to walls, and more particularly to a wall having a felted, compressedgwoven or otherwise constructed porous stratum aflixed to its masonry or other hard and unyielding surface, the said porous stratumbein covered with a layer of cementitious su stance preferably having admixed therewith a comminuted porous material, whereby the said wall will possess marked qualities of resonance and sound reilection, and reverberation be avoided therein.

I The invention is particularly applicable to masonry walls, such as those of auditoriums, theatres, concert halls, churches and the like, Where good acoustics are a prime consideration. In masonry walls as heretofore and at present constructed the solidity of the structure promotes reverberation because of the hard and unyielding character of the surface against which the sound waves are directed, and such walls are found to be almost entirely lackin in that quality of resonance so essential or the production of a ood acoustic effect.

umerous endeavors have been made to construct a Wall in such manner as to eliminate reverberation, but these structures have been based on the theory that reverberation caused by ahard unyielding surface can be counteracted only by providing a porous sound absorbing surface, whereby sound refiection is greatly reduced..- The effect thereof is to dampen or absorb the sound waves and while. such a structure does not permit of reverberation, the necessary property of resonance is absent therein.

My invention is based upon an entirely difi'erent theory; that, while reverberation must be eliminated, absorption of the sound is equally detrimental, since it is essential that the sound be clearly audible in every part of the auditorium, whether church, theatre, concert hall or the like. tion of the sound, by presenting porous surfaces against which it is directed, audibility is greatly reduced, and the acoustics are but little improved by the substitution of. one disadvantage for another, namely the elimina- With absorp- 1927. Serial No. 198,932.

tion of reverberation by absorbing and deadening the sound waves.

The principal object of my invention is to promote resonance without reverberation of sound waves by providing a wall surface having resonant properties rather than a sound deadening or absorbin character. Other objects will be apparent from the following description in which:

Figure 1 is a plan view of a wall broken airway to show the layers underlying its sur- 'ace.

Figure 2 is a vertical section made on line 22 of Figure 1.

Referring more particularly to the drawmgs: l'

A'masonry wall 10 is covered by a stratum of porous, woven or felted material 11 which is afiixed to its surface in any suitable manner. As an example of the material 11, compressed or felted hair, wadding, pulp, be gasse or other material of sufficient porosity and strength may be used. Good results have been obtained with compressed or felted sugar cane fiber. This layer 11 is covered with a coating 12 of cementitious substance, advantageously of the character disclosed in my prior U. S. Patent N 0. 1,573,475, conigrising a cementitious binder having embeded therein a comminuted porous material, such as saw dust, cork meal, asbestos, pumice or the like.

' The exercise of the present invention is not confined to the use of a cementitious coating of the composition above described, as I have obtained excellent results by admixing the cementitious substance with a fibrous ma terial such as hair, the latter preventing the wall surface from cracking as a result of the slight but constant vibration to which it is [subjected when in use. When the cementitious substance is applied to surfaces of relatively small area the addition of a fibrous or other reinforcing agent is unnecessary.

The surface coating of cement or plaster is permitted to vibrate because of the porous, relatively yielding, fibrous, and elastic character of the underlying stratum of material 11, and the capacity of the surface layer to vibrate, while at the Same time adhering perfectly to the underlying porous stratum, produces the desired acoustic effect.

The material 11 and the cement or plaster may be applied in any desired thickness, but

I have found that a thickness of approximately one-half inch of each gives excellent results.

From the foregoing it will be apparent that a wall constructed in accordance with my invention will be elastic and vibratory, and will resonate sounds directed against it by reasonof its acoustic property, yet will pre vent reverberation because its surface is not hard and unyielding as in ordinary masonry construction.

What I claim is:

1. A resonant wall consisting of a solid backing, a layer of non-resonant porous material, and a surface layer of resonant ce mentit-ious material.

2. A resonant wall consisting of a solid backing, a porous layer of fibrous material,

and a surface layer of resonant cementitious material,

3. A wall comprising a solid base, an intermediate stratum of felted fibrous porous material, and an external stratum formed of a resonant cementitious material.

it. A chamber having walls formed of a rigid base, an intermediate felted, com pressed, or woven porous stratum, and a cementitious external covering.

5. A wall structure formed of a rigid nonvibratory base, a surface stratum, and a porous stratum interposed between said base and surface stratum, and to Which said surface stratum is affixed thereby to render said surface stratum vibratory.

6. A wall structure formed of a rigid, nonvibratory base, a surface stratum, and a porous stratum interposed between said base and surface stratum and aflixed to both whereby the said surface stratum is rendered vibratory.

7. A resonant wall comprising arigid surface, a relatively yielding, porous layer overlying said surface and a cementitious external covering for said porous layer, the said surface layer being permitted to vibrate because of the elastic character of the porous material to which it is afixed,

In testimony whereof I affix my signature.

EMILE BERLINER. 

